John Hopkins on Sun, 31 May 2015 04:39:44 +0200 (CEST)

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Re: <nettime> What should GCHQ do? [was Re: nettime-l Digest, Vol

Robert -- where are you licensed to practice engineering? And in what capacity/field?

one of the rallying cries of the crypto crowd is 'trust the math.' I
don't, because math doesn't exist in the abstract. Its relationship
to engineering is obvious: engineers implement math, they make it
real, make it happen. Its relationship to law is less obvious. I

Actually, most engineers (I'm one) don't trust the math (or strictly
speaking, the physics and the math behind it).

I would challenge you to do a survey of professional engineers to prove the veracity of that statement.

Although the general statements here are gross simplifications of engineering, I definitely trust the math as an engineer (at the very least in the case of mechanics and the physics of materials). Elsewise you would never know where to start with engineering a structure. Overkill on specs can be just as bad as underkill in causing the failure of a system.

Behavior of materials under extreme conditions that they are poorly tested for (or not tested at all) certainly can end in failure, but it is not economic to test everything for every possible circumstance.

Ask any engineer. If the physics says your material such be this thick
to make it strong enough, engineers will always add a fudge factor, say
50% double the thickness, or even more. This is not a matter of math but
of empirical experience and a feel for the medium the engineer is
working with.

Any professional engineer I know would never use the term 'fudge factor' -- if you did in anything but a humorous/drunken situation, you would lose your license to practice. You would use collectively determined and specified margins of error in material properties that would be carefully carried over from a component level to a system level and all that would be considered when implementing a particular design.

The final design of the engineer in fact reflects a lack of trust for
the theory and greater reliance on experiential/empirical data.

Materials science is hardly theory -- the strength of a material fabricated in a known way is an empirically determined quantity -- stochastic, sure, but the range of properties are generally well-known for commonly used materials -- over-design is simply adding a quantified margin of error to compensate for events occurring within some statistically-determined framework of load.

Sure there are failures -- in human calculation, in human operation, and in human knowledge -- but the fact that we have the level of civilization that we have is a rather obvious demonstration of the veracity of collective engineering knowledge. (Of course, I'm not arguing that it's all 'good', but most of it it pretty damned functional. Think about it the next time you board a plane.)


Dr. John Hopkins, BSc, MFA, PhD
grounded on a granite batholith
twitter: @neoscenes

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